diff -Naur ocaml-3.10.0/asmrun/backtrace.c ocaml-3.10.0-backtrace/asmrun/backtrace.c
--- ocaml-3.10.0/asmrun/backtrace.c	2007-01-29 04:10:52.000000000 -0800
+++ ocaml-3.10.0-backtrace/asmrun/backtrace.c	2007-11-02 13:53:57.000000000 -0700
@@ -97,7 +97,7 @@
 
 /* Print a backtrace */
 
-static void print_location(int index, frame_descr * d)
+static int snprint_location(char *s, int len, int index, frame_descr * d)
 {
   uintnat infoptr;
   uint32 info1, info2, k, n, l, a, b;
@@ -106,7 +106,7 @@
   /* If no debugging information available, print nothing.
      When everything is compiled with -g, this corresponds to 
      compiler-inserted re-raise operations. */
-  if ((d->frame_size & 1) == 0) return;
+  if ((d->frame_size & 1) == 0) return 0;
   /* Recover debugging info */
   infoptr = ((uintnat) d +
              sizeof(char *) + sizeof(short) + sizeof(short) +
@@ -136,14 +136,65 @@
   else
     kind = "Called from";
 
-  fprintf(stderr, "%s file \"%s\", line %d, characters %d-%d\n",
-          kind, ((char *) infoptr) + n, l, a, b);
+  char *fmt = "%s file \"%s\", line %d, characters %d-%d\n";
+  if (s)
+    return snprintf(s, len, fmt, kind, ((char *) infoptr) + n, l, a, b);
+  else {
+    fprintf(stderr, fmt, kind, ((char *) infoptr) + n, l, a, b);
+    return 0;
+  }
 }
 
-void caml_print_exception_backtrace(void)
+static int snprint_exception_backtrace(char *s, int len)
 {
   int i;
 
+  int total_chars = 0;
   for (i = 0; i < caml_backtrace_pos; i++)
-    print_location(i, (frame_descr *) caml_backtrace_buffer[i]);
+  {
+    int chars = snprint_location(s, len, i, (frame_descr *) caml_backtrace_buffer[i]);
+    total_chars += chars;
+    s += chars;
+    len -= chars;
+  }
+  return total_chars;
+}
+
+void caml_print_exception_backtrace(void)
+{
+  snprint_exception_backtrace(0, 0);
+}
+
+CAMLprim value caml_sprint_backtrace(value sv)
+{
+  if (caml_backtrace_active)
+  {
+    int len = caml_string_length(sv);
+    char *s = String_val(sv);
+    int chars = snprint_exception_backtrace(s, len);
+    return Val_int(chars);
+  }
+  else
+    return Val_int(0);
+}
+
+CAMLprim value caml_capture_backtrace(value on)
+{
+  if (Bool_val(on))
+  {
+    caml_backtrace_active = 1;
+    caml_register_global_root(&caml_backtrace_last_exn);
+  }
+  else
+  {
+    caml_backtrace_active = 0;
+    caml_remove_global_root(&caml_backtrace_last_exn);
+    caml_backtrace_last_exn = Val_unit;
+  }
+  return Val_unit;
+}
+
+CAMLprim value caml_backtrace_captured(value unit)
+{
+  return caml_backtrace_active ? Val_true : Val_false;
 }
diff -Naur ocaml-3.10.0/bytecomp/emitcode.ml ocaml-3.10.0-backtrace/bytecomp/emitcode.ml
--- ocaml-3.10.0/bytecomp/emitcode.ml	2006-05-11 08:50:53.000000000 -0700
+++ ocaml-3.10.0-backtrace/bytecomp/emitcode.ml	2007-11-02 13:53:57.000000000 -0700
@@ -395,8 +395,9 @@
   String.unsafe_blit !out_buffer 0 code 0 !out_position;
   let reloc = List.rev !reloc_info
   and code_size = !out_position in
+  let events = !events in
   init();
-  (code, code_size, reloc)
+  (code, code_size, reloc, events)
 
 (* Emission to a file for a packed library *)
 
diff -Naur ocaml-3.10.0/bytecomp/emitcode.mli ocaml-3.10.0-backtrace/bytecomp/emitcode.mli
--- ocaml-3.10.0/bytecomp/emitcode.mli	2006-05-11 08:50:53.000000000 -0700
+++ ocaml-3.10.0-backtrace/bytecomp/emitcode.mli	2007-11-02 13:53:57.000000000 -0700
@@ -23,7 +23,7 @@
              name of compilation unit implemented
              list of instructions to emit *)
 val to_memory: instruction list -> instruction list ->
-                    string * int * (reloc_info * int) list
+                    string * int * (reloc_info * int) list * debug_event list
         (* Arguments:
              initialization code (terminated by STOP)
              function code
diff -Naur ocaml-3.10.0/bytecomp/meta.ml ocaml-3.10.0-backtrace/bytecomp/meta.ml
--- ocaml-3.10.0/bytecomp/meta.ml	2004-04-16 06:46:20.000000000 -0700
+++ ocaml-3.10.0-backtrace/bytecomp/meta.ml	2007-11-02 13:53:57.000000000 -0700
@@ -24,3 +24,6 @@
                                 = "caml_invoke_traced_function"
 external get_section_table : unit -> (string * Obj.t) list
                                 = "caml_get_section_table"
+
+external add_debug_info : string -> int -> Instruct.debug_event list array -> unit = "caml_add_debug_info"
+external remove_debug_info : string -> unit = "caml_remove_debug_info"
diff -Naur ocaml-3.10.0/bytecomp/meta.mli ocaml-3.10.0-backtrace/bytecomp/meta.mli
--- ocaml-3.10.0/bytecomp/meta.mli	2004-04-16 06:46:27.000000000 -0700
+++ ocaml-3.10.0-backtrace/bytecomp/meta.mli	2007-11-02 13:53:57.000000000 -0700
@@ -26,3 +26,8 @@
                                 = "caml_invoke_traced_function"
 external get_section_table : unit -> (string * Obj.t) list
                                 = "caml_get_section_table"
+external add_debug_info : string -> int -> Instruct.debug_event list array -> unit
+                                = "caml_add_debug_info"
+external remove_debug_info : string -> unit
+                                = "caml_remove_debug_info"
+
diff -Naur ocaml-3.10.0/byterun/backtrace.c ocaml-3.10.0-backtrace/byterun/backtrace.c
--- ocaml-3.10.0/byterun/backtrace.c	2007-01-29 04:11:15.000000000 -0800
+++ ocaml-3.10.0-backtrace/byterun/backtrace.c	2007-11-02 13:53:57.000000000 -0700
@@ -38,6 +38,7 @@
 CAMLexport int caml_backtrace_pos = 0;
 CAMLexport code_t * caml_backtrace_buffer = NULL;
 CAMLexport value caml_backtrace_last_exn = Val_unit;
+CAMLexport value caml_debug_info = Val_emptylist;
 #define BACKTRACE_BUFFER_SIZE 1024
 
 /* Location of fields in the Instruct.debug_event record */
@@ -59,6 +60,49 @@
   POS_CNUM = 3
 };
 
+/* Location of fields in the caml_debug_info records */;
+enum {
+  DI_START = 0,
+  DI_SIZE = 1,
+  DI_EVENTS = 2
+};
+
+CAMLprim value caml_add_debug_info(code_t start, value size, value events)
+{
+  CAMLparam1(events);
+  CAMLlocal1(debug_info);
+  debug_info = caml_alloc(3, 0);
+  Store_field(debug_info, DI_START, (value)start);
+  Store_field(debug_info, DI_SIZE, size);
+  Store_field(debug_info, DI_EVENTS, events);
+  value cons = caml_alloc(2, 0);
+  Store_field(cons, 0, debug_info);
+  Store_field(cons, 1, caml_debug_info);
+  caml_debug_info = cons;
+  CAMLreturn(Val_unit);
+}
+
+CAMLprim value caml_remove_debug_info(code_t start)
+{
+  CAMLparam0();
+  value dis = caml_debug_info;
+  value prev = 0;
+  while (dis != Val_emptylist) {
+    value di = Field(dis, 0);
+    code_t di_start = (code_t)Field(di, DI_START);
+    if (di_start == start) {
+      if (prev)
+	Store_field(prev, 1, Field(dis, 1));
+      else
+	caml_debug_info = Field(dis, 1);
+      break;
+    }
+    prev = di;
+    dis = Field(dis, 1);
+  }
+  CAMLreturn(Val_unit);
+}
+
 /* Initialize the backtrace machinery */
 
 void caml_init_backtrace(void)
@@ -74,7 +118,6 @@
 
 void caml_stash_backtrace(value exn, code_t pc, value * sp)
 {
-  code_t end_code = (code_t) ((char *) caml_start_code + caml_code_size);
   if (pc != NULL) pc = pc - 1;
   if (exn != caml_backtrace_last_exn) {
     caml_backtrace_pos = 0;
@@ -85,14 +128,30 @@
     if (caml_backtrace_buffer == NULL) return;
   }
   if (caml_backtrace_pos >= BACKTRACE_BUFFER_SIZE) return;
-  if (pc >= caml_start_code && pc < end_code){
-    caml_backtrace_buffer[caml_backtrace_pos++] = pc;
+  value dis = caml_debug_info;
+  while (dis != Val_emptylist) {
+    value di = Field(dis, 0);
+    code_t start = (code_t)Field(di, DI_START);
+    code_t end = start + Int_val(Field(di, DI_SIZE));
+    if (pc >= start && pc < end){
+      caml_backtrace_buffer[caml_backtrace_pos++] = pc;
+      break;
+    }
+    dis = Field(dis, 1);
   }
   for (/*nothing*/; sp < caml_trapsp; sp++) {
+    if (caml_backtrace_pos >= BACKTRACE_BUFFER_SIZE) break;
     code_t p = (code_t) *sp;
-    if (p >= caml_start_code && p < end_code) {
-      if (caml_backtrace_pos >= BACKTRACE_BUFFER_SIZE) break;
-      caml_backtrace_buffer[caml_backtrace_pos++] = p;
+    value dis = caml_debug_info;
+    while (dis != Val_emptylist) {
+      value di = Field(dis, 0);
+      code_t start = (code_t)Field(di, DI_START);
+      code_t end = start + Int_val(Field(di, DI_SIZE));
+      if (p >= start && p < end) {
+	caml_backtrace_buffer[caml_backtrace_pos++] = p;
+	break;
+      }
+      dis = Field(dis, 1);
     }
   }
 }
@@ -105,79 +164,87 @@
 #define O_BINARY 0
 #endif
 
-static value read_debug_info(void)
+CAMLexport void caml_read_debug_info(int fd, struct exec_trailer *trail)
 {
   CAMLparam0();
   CAMLlocal1(events);
-  char * exec_name;
-  int fd;
-  struct exec_trailer trail;
   struct channel * chan;
   uint32 num_events, orig, i;
   value evl, l;
 
-  exec_name = caml_exe_name;
-  fd = caml_attempt_open(&exec_name, &trail, 1);
-  if (fd < 0) CAMLreturn(Val_false);
-  caml_read_section_descriptors(fd, &trail);
-  if (caml_seek_optional_section(fd, &trail, "DBUG") == -1) {
-    close(fd);
-    CAMLreturn(Val_false);
-  }
-  chan = caml_open_descriptor_in(fd);
-  num_events = caml_getword(chan);
-  events = caml_alloc(num_events, 0);
-  for (i = 0; i < num_events; i++) {
-    orig = caml_getword(chan);
-    evl = caml_input_val(chan);
-    /* Relocate events in event list */
-    for (l = evl; l != Val_int(0); l = Field(l, 1)) {
-      value ev = Field(l, 0);
-      Field(ev, EV_POS) = Val_long(Long_val(Field(ev, EV_POS)) + orig);
+  caml_register_global_root(&caml_debug_info);
+
+  if (caml_seek_optional_section(fd, trail, "DBUG") == -1)
+    events = caml_alloc(0, 0);
+
+  else {
+    chan = caml_open_descriptor_in(fd);
+    num_events = caml_getword(chan);
+    events = caml_alloc(num_events, 0);
+    for (i = 0; i < num_events; i++) {
+      orig = caml_getword(chan);
+      evl = caml_input_val(chan);
+      /* Relocate events in event list */
+      for (l = evl; l != Val_int(0); l = Field(l, 1)) {
+	value ev = Field(l, 0);
+	Field(ev, EV_POS) = Val_long(Long_val(Field(ev, EV_POS)) + orig);
+      }
+      /* Record event list */
+      Store_field(events, i, evl);
     }
-    /* Record event list */
-    Store_field(events, i, evl);
+    caml_release_channel(chan);
   }
-  caml_close_channel(chan);
-  CAMLreturn(events);
+
+  caml_add_debug_info(caml_start_code, Val_int(caml_code_size), events);
+  CAMLreturn0;
 }
 
 /* Search the event for the given PC.  Return Val_false if not found. */
 
-static value event_for_location(value events, code_t pc)
+static value event_for_location(code_t pc)
 {
   mlsize_t i;
   value pos, l, ev, ev_pos, best_ev;
 
   best_ev = 0;
-  Assert(pc >= caml_start_code && pc < caml_start_code + caml_code_size);
-  pos = Val_long((char *) pc - (char *) caml_start_code);
-  for (i = 0; i < Wosize_val(events); i++) {
-    for (l = Field(events, i); l != Val_int(0); l = Field(l, 1)) {
-      ev = Field(l, 0);
-      ev_pos = Field(ev, EV_POS);
-      if (ev_pos == pos) return ev;
-      /* ocamlc sometimes moves an event past a following PUSH instruction;
-         allow mismatch by 1 instruction. */
-      if (ev_pos == pos + 8) best_ev = ev;
+  value dis = caml_debug_info;
+  while (dis != Val_emptylist) {
+    value di = Field(dis, 0);
+    code_t start = (code_t)Field(di, DI_START);
+    code_t end = start + Int_val(Field(di, DI_SIZE));
+    if (start <= pc && pc < end) {
+      value events = Field(di, DI_EVENTS);
+      pos = Val_long((char *) pc - (char *) start);
+      for (i = 0; i < Wosize_val(events); i++) {
+	for (l = Field(events, i); l != Val_int(0); l = Field(l, 1)) {
+	  ev = Field(l, 0);
+	  ev_pos = Field(ev, EV_POS);
+	  if (ev_pos == pos) return ev;
+	  /* ocamlc sometimes moves an event past a following PUSH instruction;
+	     allow mismatch by 1 instruction. */
+	  if (ev_pos == pos + 8) best_ev = ev;
+	}
+      }
+      if (best_ev != 0) return best_ev;
+      return Val_false;
     }
+    dis = Field(dis, 1);
   }
-  if (best_ev != 0) return best_ev;
   return Val_false;
 }
 
 /* Print the location corresponding to the given PC */
 
-static void print_location(value events, int index)
+static int snprint_location(char *s, int len, int index)
 {
    code_t pc = caml_backtrace_buffer[index];
   char * info;
   value ev;
 
-  ev = event_for_location(events, pc);
+  ev = event_for_location(pc);
   if (caml_is_instruction(*pc, RAISE)) {
     /* Ignore compiler-inserted raise */
-    if (ev == Val_false) return;
+    if (ev == Val_false) return 0;
     /* Initial raise if index == 0, re-raise otherwise */
     if (index == 0)
       info = "Raised at";
@@ -190,7 +257,13 @@
       info = "Called from";
   }
   if (ev == Val_false) {
-    fprintf(stderr, "%s unknown location\n", info);
+    char *fmt = "%s unknown location\n";
+    if (s)
+      return snprintf(s, len, fmt, info);
+    else {
+      fprintf(stderr, fmt, info);
+      return 0;
+    }
   } else {
     value ev_start = Field (Field (ev, EV_LOC), LOC_START);
     char *fname = String_val (Field (ev_start, POS_FNAME));
@@ -199,24 +272,68 @@
                    - Int_val (Field (ev_start, POS_BOL));
     int endchr = Int_val (Field (Field (Field (ev, EV_LOC), LOC_END), POS_CNUM))
                  - Int_val (Field (ev_start, POS_BOL));
-    fprintf (stderr, "%s file \"%s\", line %d, characters %d-%d\n", info, fname,
-             lnum, startchr, endchr);
+    char *fmt = "%s file \"%s\", line %d, characters %d-%d\n";
+    if (s)
+      return snprintf (s, len, fmt, info, fname, lnum, startchr, endchr);
+    else {
+      fprintf (stderr, fmt, info, fname,lnum, startchr, endchr);
+      return 0;
+    }
   }
 }
 
 /* Print a backtrace */
 
-CAMLexport void caml_print_exception_backtrace(void)
+static int snprint_exception_backtrace(char *s, int len)
 {
-  value events;
   int i;
 
-  events = read_debug_info();
-  if (events == Val_false) {
-    fprintf(stderr,
-            "(Program not linked with -g, cannot print stack backtrace)\n");
-    return;
-  }
+  int total_chars = 0;
   for (i = 0; i < caml_backtrace_pos; i++)
-    print_location(events, i);
+  {
+    int chars = snprint_location(s, len, i);
+    total_chars += chars;
+    s += chars;
+    len -= chars;
+  }
+  return total_chars;
+}
+
+CAMLexport void caml_print_exception_backtrace(void)
+{
+  snprint_exception_backtrace(0, 0);
+}
+
+CAMLprim value caml_sprint_backtrace(value sv)
+{
+  if (caml_backtrace_active)
+  {
+    int len = caml_string_length(sv);
+    char *s = String_val(sv);
+    int chars = snprint_exception_backtrace(s, len);
+    return Val_int(chars);
+  }
+  else
+    return Val_int(0);
+}
+
+CAMLprim value caml_capture_backtrace(value on)
+{
+  if (Bool_val(on))
+  {
+    caml_backtrace_active = 1;
+    caml_register_global_root(&caml_backtrace_last_exn);
+  }
+  else
+  {
+    caml_backtrace_active = 0;
+    caml_remove_global_root(&caml_backtrace_last_exn);
+    caml_backtrace_last_exn = Val_unit;
+  }
+  return Val_unit;
+}
+
+CAMLprim value caml_backtrace_captured(value unit)
+{
+  return caml_backtrace_active ? Val_true : Val_false;
 }
diff -Naur ocaml-3.10.0/byterun/backtrace.h ocaml-3.10.0-backtrace/byterun/backtrace.h
--- ocaml-3.10.0/byterun/backtrace.h	2007-01-29 04:11:15.000000000 -0800
+++ ocaml-3.10.0-backtrace/byterun/backtrace.h	2007-11-02 13:53:57.000000000 -0700
@@ -17,6 +17,7 @@
 #define CAML_BACKTRACE_H
 
 #include "mlvalues.h"
+#include "exec.h"
 
 CAMLextern int caml_backtrace_active;
 CAMLextern int caml_backtrace_pos;
@@ -28,5 +29,6 @@
 extern void caml_stash_backtrace(value exn, code_t pc, value * sp);
 #endif
 CAMLextern void caml_print_exception_backtrace(void);
+CAMLextern void caml_read_debug_info(int fd, struct exec_trailer *trail);
 
 #endif /* CAML_BACKTRACE_H */
diff -Naur ocaml-3.10.0/byterun/io.c ocaml-3.10.0-backtrace/byterun/io.c
--- ocaml-3.10.0/byterun/io.c	2007-02-25 04:38:36.000000000 -0800
+++ ocaml-3.10.0-backtrace/byterun/io.c	2007-11-02 13:53:57.000000000 -0700
@@ -103,6 +103,12 @@
 CAMLexport void caml_close_channel(struct channel *channel)
 {
   close(channel->fd);
+  caml_release_channel(channel);
+}
+
+/* release the channel but leave the file descriptor open */
+CAMLexport void caml_release_channel(struct channel *channel)
+{
   if (channel->refcount > 0) return;
   if (caml_channel_mutex_free != NULL) (*caml_channel_mutex_free)(channel);
   unlink_channel(channel);
diff -Naur ocaml-3.10.0/byterun/io.h ocaml-3.10.0-backtrace/byterun/io.h
--- ocaml-3.10.0/byterun/io.h	2006-09-20 10:37:08.000000000 -0700
+++ ocaml-3.10.0-backtrace/byterun/io.h	2007-11-02 13:53:57.000000000 -0700
@@ -77,6 +77,7 @@
 CAMLextern struct channel * caml_open_descriptor_in (int);
 CAMLextern struct channel * caml_open_descriptor_out (int);
 CAMLextern void caml_close_channel (struct channel *);
+CAMLextern void caml_release_channel (struct channel *);
 CAMLextern int caml_channel_binary_mode (struct channel *);
 CAMLextern value caml_alloc_channel(struct channel *chan);
 
diff -Naur ocaml-3.10.0/byterun/Makefile ocaml-3.10.0-backtrace/byterun/Makefile
--- ocaml-3.10.0/byterun/Makefile	2007-02-23 01:29:45.000000000 -0800
+++ ocaml-3.10.0-backtrace/byterun/Makefile	2007-08-02 12:25:23.000000000 -0700
@@ -29,7 +29,7 @@
 
 DOBJS=$(OBJS:.o=.d.o) instrtrace.d.o
 
-PRIMS=alloc.c array.c compare.c extern.c floats.c gc_ctrl.c hash.c \
+PRIMS=alloc.c array.c backtrace.c compare.c extern.c floats.c gc_ctrl.c hash.c \
   intern.c interp.c ints.c io.c lexing.c md5.c meta.c obj.c parsing.c \
   signals.c str.c sys.c terminfo.c callback.c weak.c finalise.c stacks.c \
   dynlink.c
diff -Naur ocaml-3.10.0/byterun/startup.c ocaml-3.10.0-backtrace/byterun/startup.c
--- ocaml-3.10.0/byterun/startup.c	2005-09-22 07:21:50.000000000 -0700
+++ ocaml-3.10.0-backtrace/byterun/startup.c	2007-11-02 13:53:57.000000000 -0700
@@ -392,6 +392,7 @@
   caml_stat_free(shared_lib_path);
   caml_stat_free(shared_libs);
   caml_stat_free(req_prims);
+  caml_read_debug_info(fd, &trail);
   /* Load the globals */
   caml_seek_section(fd, &trail, "DATA");
   chan = caml_open_descriptor_in(fd);
diff -Naur ocaml-3.10.0/.depend ocaml-3.10.0-backtrace/.depend
--- ocaml-3.10.0/.depend	2007-03-02 14:47:05.000000000 -0800
+++ ocaml-3.10.0-backtrace/.depend	2007-11-02 13:53:57.000000000 -0700
@@ -274,6 +274,7 @@
     parsing/location.cmi typing/ident.cmi typing/env.cmi parsing/asttypes.cmi 
 bytecomp/matching.cmi: typing/typedtree.cmi parsing/location.cmi \
     bytecomp/lambda.cmi typing/ident.cmi parsing/asttypes.cmi 
+bytecomp/meta.cmi: bytecomp/instruct.cmi 
 bytecomp/printinstr.cmi: bytecomp/instruct.cmi 
 bytecomp/printlambda.cmi: bytecomp/lambda.cmi 
 bytecomp/simplif.cmi: bytecomp/lambda.cmi 
@@ -356,8 +357,8 @@
     typing/primitive.cmx typing/predef.cmx typing/parmatch.cmx utils/misc.cmx \
     parsing/location.cmx bytecomp/lambda.cmx typing/ident.cmx \
     typing/btype.cmx parsing/asttypes.cmi bytecomp/matching.cmi 
-bytecomp/meta.cmo: bytecomp/meta.cmi 
-bytecomp/meta.cmx: bytecomp/meta.cmi 
+bytecomp/meta.cmo: bytecomp/instruct.cmi bytecomp/meta.cmi 
+bytecomp/meta.cmx: bytecomp/instruct.cmx bytecomp/meta.cmi 
 bytecomp/printinstr.cmo: bytecomp/printlambda.cmi parsing/location.cmi \
     bytecomp/lambda.cmi bytecomp/instruct.cmi typing/ident.cmi \
     bytecomp/printinstr.cmi 
@@ -443,14 +444,14 @@
 asmcomp/clambda.cmi: bytecomp/lambda.cmi typing/ident.cmi \
     asmcomp/debuginfo.cmi parsing/asttypes.cmi 
 asmcomp/closure.cmi: bytecomp/lambda.cmi asmcomp/clambda.cmi 
-asmcomp/cmm.cmi: typing/ident.cmi asmcomp/debuginfo.cmi 
 asmcomp/cmmgen.cmi: asmcomp/cmm.cmi asmcomp/clambda.cmi 
+asmcomp/cmm.cmi: typing/ident.cmi asmcomp/debuginfo.cmi 
 asmcomp/codegen.cmi: asmcomp/cmm.cmi 
 asmcomp/comballoc.cmi: asmcomp/mach.cmi 
 asmcomp/compilenv.cmi: typing/ident.cmi asmcomp/clambda.cmi 
 asmcomp/debuginfo.cmi: parsing/location.cmi bytecomp/lambda.cmi 
-asmcomp/emit.cmi: asmcomp/linearize.cmi asmcomp/cmm.cmi 
 asmcomp/emitaux.cmi: asmcomp/debuginfo.cmi 
+asmcomp/emit.cmi: asmcomp/linearize.cmi asmcomp/cmm.cmi 
 asmcomp/interf.cmi: asmcomp/mach.cmi 
 asmcomp/linearize.cmi: asmcomp/reg.cmi asmcomp/mach.cmi asmcomp/debuginfo.cmi 
 asmcomp/liveness.cmi: asmcomp/mach.cmi 
@@ -461,8 +462,8 @@
 asmcomp/printmach.cmi: asmcomp/reg.cmi asmcomp/mach.cmi 
 asmcomp/proc.cmi: asmcomp/reg.cmi asmcomp/mach.cmi 
 asmcomp/reg.cmi: asmcomp/cmm.cmi 
-asmcomp/reload.cmi: asmcomp/mach.cmi 
 asmcomp/reloadgen.cmi: asmcomp/reg.cmi asmcomp/mach.cmi 
+asmcomp/reload.cmi: asmcomp/mach.cmi 
 asmcomp/schedgen.cmi: asmcomp/mach.cmi asmcomp/linearize.cmi 
 asmcomp/scheduling.cmi: asmcomp/linearize.cmi 
 asmcomp/selectgen.cmi: utils/tbl.cmi asmcomp/reg.cmi asmcomp/mach.cmi \
@@ -526,10 +527,6 @@
     utils/misc.cmx bytecomp/lambda.cmx typing/ident.cmx asmcomp/debuginfo.cmx \
     asmcomp/compilenv.cmx utils/clflags.cmx asmcomp/clambda.cmx \
     parsing/asttypes.cmi asmcomp/closure.cmi 
-asmcomp/cmm.cmo: typing/ident.cmi asmcomp/debuginfo.cmi asmcomp/arch.cmo \
-    asmcomp/cmm.cmi 
-asmcomp/cmm.cmx: typing/ident.cmx asmcomp/debuginfo.cmx asmcomp/arch.cmx \
-    asmcomp/cmm.cmi 
 asmcomp/cmmgen.cmo: typing/types.cmi bytecomp/switch.cmi asmcomp/proc.cmi \
     typing/primitive.cmi utils/misc.cmi bytecomp/lambda.cmi typing/ident.cmi \
     asmcomp/debuginfo.cmi utils/config.cmi asmcomp/compilenv.cmi \
@@ -540,6 +537,10 @@
     asmcomp/debuginfo.cmx utils/config.cmx asmcomp/compilenv.cmx \
     asmcomp/cmm.cmx utils/clflags.cmx asmcomp/clambda.cmx \
     parsing/asttypes.cmi asmcomp/arch.cmx asmcomp/cmmgen.cmi 
+asmcomp/cmm.cmo: typing/ident.cmi asmcomp/debuginfo.cmi asmcomp/arch.cmo \
+    asmcomp/cmm.cmi 
+asmcomp/cmm.cmx: typing/ident.cmx asmcomp/debuginfo.cmx asmcomp/arch.cmx \
+    asmcomp/cmm.cmi 
 asmcomp/codegen.cmo: asmcomp/split.cmi asmcomp/spill.cmi asmcomp/reload.cmi \
     asmcomp/reg.cmi asmcomp/printmach.cmi asmcomp/printlinear.cmi \
     asmcomp/printcmm.cmi asmcomp/liveness.cmi asmcomp/linearize.cmi \
@@ -564,6 +565,12 @@
     asmcomp/debuginfo.cmi 
 asmcomp/debuginfo.cmx: parsing/location.cmx bytecomp/lambda.cmx \
     asmcomp/debuginfo.cmi 
+asmcomp/emitaux.cmo: asmcomp/reg.cmi asmcomp/linearize.cmi \
+    asmcomp/debuginfo.cmi asmcomp/cmm.cmi asmcomp/arch.cmo \
+    asmcomp/emitaux.cmi 
+asmcomp/emitaux.cmx: asmcomp/reg.cmx asmcomp/linearize.cmx \
+    asmcomp/debuginfo.cmx asmcomp/cmm.cmx asmcomp/arch.cmx \
+    asmcomp/emitaux.cmi 
 asmcomp/emit.cmo: asmcomp/reg.cmi asmcomp/proc.cmi utils/misc.cmi \
     asmcomp/mach.cmi parsing/location.cmi asmcomp/linearize.cmi \
     asmcomp/emitaux.cmi asmcomp/debuginfo.cmi utils/config.cmi \
@@ -574,12 +581,6 @@
     asmcomp/emitaux.cmx asmcomp/debuginfo.cmx utils/config.cmx \
     asmcomp/compilenv.cmx asmcomp/cmm.cmx utils/clflags.cmx asmcomp/arch.cmx \
     asmcomp/emit.cmi 
-asmcomp/emitaux.cmo: asmcomp/reg.cmi asmcomp/linearize.cmi \
-    asmcomp/debuginfo.cmi asmcomp/cmm.cmi asmcomp/arch.cmo \
-    asmcomp/emitaux.cmi 
-asmcomp/emitaux.cmx: asmcomp/reg.cmx asmcomp/linearize.cmx \
-    asmcomp/debuginfo.cmx asmcomp/cmm.cmx asmcomp/arch.cmx \
-    asmcomp/emitaux.cmi 
 asmcomp/interf.cmo: asmcomp/reg.cmi asmcomp/proc.cmi utils/misc.cmi \
     asmcomp/mach.cmi asmcomp/interf.cmi 
 asmcomp/interf.cmx: asmcomp/reg.cmx asmcomp/proc.cmx utils/misc.cmx \
@@ -620,14 +621,14 @@
     asmcomp/arch.cmx asmcomp/proc.cmi 
 asmcomp/reg.cmo: asmcomp/cmm.cmi asmcomp/reg.cmi 
 asmcomp/reg.cmx: asmcomp/cmm.cmx asmcomp/reg.cmi 
-asmcomp/reload.cmo: asmcomp/reloadgen.cmi asmcomp/reg.cmi asmcomp/mach.cmi \
-    asmcomp/cmm.cmi asmcomp/arch.cmo asmcomp/reload.cmi 
-asmcomp/reload.cmx: asmcomp/reloadgen.cmx asmcomp/reg.cmx asmcomp/mach.cmx \
-    asmcomp/cmm.cmx asmcomp/arch.cmx asmcomp/reload.cmi 
 asmcomp/reloadgen.cmo: asmcomp/reg.cmi utils/misc.cmi asmcomp/mach.cmi \
     asmcomp/reloadgen.cmi 
 asmcomp/reloadgen.cmx: asmcomp/reg.cmx utils/misc.cmx asmcomp/mach.cmx \
     asmcomp/reloadgen.cmi 
+asmcomp/reload.cmo: asmcomp/reloadgen.cmi asmcomp/reg.cmi asmcomp/mach.cmi \
+    asmcomp/cmm.cmi asmcomp/arch.cmo asmcomp/reload.cmi 
+asmcomp/reload.cmx: asmcomp/reloadgen.cmx asmcomp/reg.cmx asmcomp/mach.cmx \
+    asmcomp/cmm.cmx asmcomp/arch.cmx asmcomp/reload.cmi 
 asmcomp/schedgen.cmo: asmcomp/reg.cmi utils/misc.cmi asmcomp/mach.cmi \
     asmcomp/linearize.cmi asmcomp/cmm.cmi asmcomp/arch.cmo \
     asmcomp/schedgen.cmi 
@@ -686,6 +687,8 @@
     parsing/location.cmx parsing/lexer.cmx typing/includemod.cmx \
     typing/env.cmx typing/ctype.cmx bytecomp/bytepackager.cmx \
     bytecomp/bytelink.cmx bytecomp/bytelibrarian.cmx driver/errors.cmi 
+driver/main_args.cmo: driver/main_args.cmi 
+driver/main_args.cmx: driver/main_args.cmi 
 driver/main.cmo: utils/warnings.cmi utils/misc.cmi driver/main_args.cmi \
     driver/errors.cmi utils/config.cmi driver/compile.cmi utils/clflags.cmi \
     bytecomp/bytepackager.cmi bytecomp/bytelink.cmi \
@@ -694,8 +697,6 @@
     driver/errors.cmx utils/config.cmx driver/compile.cmx utils/clflags.cmx \
     bytecomp/bytepackager.cmx bytecomp/bytelink.cmx \
     bytecomp/bytelibrarian.cmx driver/main.cmi 
-driver/main_args.cmo: driver/main_args.cmi 
-driver/main_args.cmx: driver/main_args.cmi 
 driver/optcompile.cmo: utils/warnings.cmi typing/unused_var.cmi \
     typing/typemod.cmi typing/typedtree.cmi bytecomp/translmod.cmi \
     bytecomp/simplif.cmi typing/printtyp.cmi bytecomp/printlambda.cmi \
diff -Naur ocaml-3.10.0/Makefile ocaml-3.10.0-backtrace/Makefile
--- ocaml-3.10.0/Makefile	2007-04-16 09:01:59.000000000 -0700
+++ ocaml-3.10.0-backtrace/Makefile	2007-11-02 13:53:57.000000000 -0700
@@ -19,8 +19,8 @@
 
 CAMLC=boot/ocamlrun boot/ocamlc -nostdlib -I boot
 CAMLOPT=boot/ocamlrun ./ocamlopt -nostdlib -I stdlib
-COMPFLAGS=-warn-error A $(INCLUDES)
-LINKFLAGS=
+COMPFLAGS=-g -warn-error A $(INCLUDES)
+LINKFLAGS=-g
 
 CAMLYACC=boot/ocamlyacc
 YACCFLAGS=-v
diff -Naur ocaml-3.10.0/otherlibs/dynlink/dynlink.ml ocaml-3.10.0-backtrace/otherlibs/dynlink/dynlink.ml
--- ocaml-3.10.0/otherlibs/dynlink/dynlink.ml	2006-09-28 14:36:38.000000000 -0700
+++ ocaml-3.10.0-backtrace/otherlibs/dynlink/dynlink.ml	2007-11-02 13:53:57.000000000 -0700
@@ -176,6 +176,13 @@
       | _ -> assert false in
     raise(Error(Linking_error (file_name, new_error)))
   end;
+  let events =
+    if compunit.cu_debug = 0 then [| |]
+    else begin
+      seek_in ic compunit.cu_debug;
+      [| input_value ic |]
+    end in
+  Meta.add_debug_info code code_size events;
   begin try
     ignore((Meta.reify_bytecode code code_size) ())
   with exn ->
diff -Naur ocaml-3.10.0/stdlib/printexc.ml ocaml-3.10.0-backtrace/stdlib/printexc.ml
--- ocaml-3.10.0/stdlib/printexc.ml	2004-01-16 07:24:02.000000000 -0800
+++ ocaml-3.10.0-backtrace/stdlib/printexc.ml	2007-11-02 13:53:57.000000000 -0700
@@ -13,6 +13,10 @@
 
 (* $Id: printexc.ml,v 1.18 2004/01/16 15:24:02 doligez Exp $ *)
 
+external capture_backtrace : bool -> unit = "caml_capture_backtrace";;
+external backtrace_captured : unit -> bool = "caml_backtrace_captured";;
+external sprint_backtrace : string -> int = "caml_sprint_backtrace";;
+
 open Printf;;
 
 let locfmt = format_of_string "File \"%s\", line %d, characters %d-%d: %s";;
diff -Naur ocaml-3.10.0/stdlib/printexc.mli ocaml-3.10.0-backtrace/stdlib/printexc.mli
--- ocaml-3.10.0/stdlib/printexc.mli	2005-10-25 11:34:07.000000000 -0700
+++ ocaml-3.10.0-backtrace/stdlib/printexc.mli	2007-12-31 15:09:41.000000000 -0800
@@ -15,6 +15,20 @@
 
 (** Facilities for printing exceptions. *)
 
+(* UNCOMMENT
+val capture_backtrace : bool -> unit
+(** [Printexc.capture_backtrace b] turns the capturing of backtraces
+   on if [b] is true, otherwise turns it off. *)
+
+val backtrace_captured : unit -> bool
+(** [Printexc.backtrace_captured ()] returns true iff capturing
+  backtraces is on. *)
+
+val sprint_backtrace : string -> int
+(** [Printexc.sprint_backtrace s] prints the latest exception
+   backtrace into [s] and returns the number of characters written. *)
+UNCOMMENT *)
+
 val to_string : exn -> string
 (** [Printexc.to_string e] returns a string representation of
    the exception [e]. *)
diff -Naur ocaml-3.10.0/toplevel/topdirs.ml ocaml-3.10.0-backtrace/toplevel/topdirs.ml
--- ocaml-3.10.0/toplevel/topdirs.ml	2006-09-28 14:36:38.000000000 -0700
+++ ocaml-3.10.0-backtrace/toplevel/topdirs.ml	2007-11-02 13:53:57.000000000 -0700
@@ -74,11 +74,19 @@
   let initial_symtable = Symtable.current_state() in
   Symtable.patch_object code compunit.cu_reloc;
   Symtable.update_global_table();
+  let events =
+    if compunit.cu_debug = 0 then [| |]
+    else begin
+      seek_in ic compunit.cu_debug;
+      [| input_value ic |]
+    end in
+  Meta.add_debug_info code code_size events;
   begin try
     may_trace := true;
     ignore((Meta.reify_bytecode code code_size) ());
     may_trace := false;
   with exn ->
+    capture_backtrace ();
     may_trace := false;
     Symtable.restore_state initial_symtable;
     print_exception_outcome ppf exn;
@@ -298,4 +306,10 @@
              (Directive_string (parse_warnings std_out false));
 
   Hashtbl.add directive_table "warn_error"
-             (Directive_string (parse_warnings std_out true))
+             (Directive_string (parse_warnings std_out true));
+
+  Hashtbl.add directive_table "debug"
+             (Directive_bool(fun b -> Clflags.debug := b));
+
+  Hashtbl.add directive_table "capture_backtrace"
+             (Directive_bool(fun b -> Printexc.capture_backtrace b))
diff -Naur ocaml-3.10.0/toplevel/toploop.ml ocaml-3.10.0-backtrace/toplevel/toploop.ml
--- ocaml-3.10.0/toplevel/toploop.ml	2006-01-04 08:55:50.000000000 -0800
+++ ocaml-3.10.0-backtrace/toplevel/toploop.ml	2007-11-02 13:53:57.000000000 -0700
@@ -113,6 +113,13 @@
 let may_trace = ref false (* Global lock on tracing *)
 type evaluation_outcome = Result of Obj.t | Exception of exn
 
+let backtrace = String.create 8192
+let backtrace_length = ref 0
+
+let capture_backtrace () =
+  if Printexc.backtrace_captured ()
+  then backtrace_length := Printexc.sprint_backtrace backtrace
+
 let load_lambda ppf lam =
   if !Clflags.dump_rawlambda then fprintf ppf "%a@." Printlambda.lambda lam;
   let slam = Simplif.simplify_lambda lam in
@@ -122,7 +129,8 @@
     fprintf ppf "%a%a@."
     Printinstr.instrlist init_code
     Printinstr.instrlist fun_code;
-  let (code, code_size, reloc) = Emitcode.to_memory init_code fun_code in
+  let (code, code_size, reloc, events) = Emitcode.to_memory init_code fun_code in
+  Meta.add_debug_info code code_size [| events |];
   let can_free = (fun_code = []) in
   let initial_symtable = Symtable.current_state() in
   Symtable.patch_object code reloc;
@@ -133,13 +141,16 @@
     let retval = (Meta.reify_bytecode code code_size) () in
     may_trace := false;
     if can_free then begin
+      Meta.remove_debug_info code;
       Meta.static_release_bytecode code code_size;
       Meta.static_free code;
     end;
     Result retval
   with x ->
+    capture_backtrace ();
     may_trace := false;
     if can_free then begin
+      Meta.remove_debug_info code;
       Meta.static_release_bytecode code code_size;
       Meta.static_free code;
     end;
@@ -203,7 +214,13 @@
 let print_exception_outcome ppf exn =
   if exn = Out_of_memory then Gc.full_major ();
   let outv = outval_of_value !toplevel_env (Obj.repr exn) Predef.type_exn in
-  print_out_exception ppf exn outv
+  print_out_exception ppf exn outv;
+  if Printexc.backtrace_captured()
+  then begin
+    if !backtrace_length > 0
+    then print_string (String.sub backtrace 0 !backtrace_length);
+    backtrace_length := 0
+  end
 
 (* The table of toplevel directives.
    Filled by functions from module topdirs. *)
@@ -247,6 +264,15 @@
               Ophr_exception (exn, outv)
         in
         !print_out_phrase ppf out_phr;
+        if Printexc.backtrace_captured()
+        then begin
+          if !backtrace_length > 0
+          then begin
+            pp_print_string ppf (String.sub backtrace 0 !backtrace_length);
+            pp_print_flush ppf ();
+            backtrace_length := 0;
+          end;
+        end;
         begin match out_phr with
         | Ophr_eval (_, _) | Ophr_signature _ -> true
         | Ophr_exception _ -> false
diff -Naur ocaml-3.10.0/toplevel/toploop.mli ocaml-3.10.0-backtrace/toplevel/toploop.mli
--- ocaml-3.10.0/toplevel/toploop.mli	2004-05-15 02:59:37.000000000 -0700
+++ ocaml-3.10.0-backtrace/toplevel/toploop.mli	2007-11-02 13:53:57.000000000 -0700
@@ -62,6 +62,7 @@
            [use_silently] does not print them. *)
 val eval_path: Path.t -> Obj.t
         (* Return the toplevel object referred to by the given path *)
+val capture_backtrace: unit -> unit
 
 (* Printing of values *)